packet: only test po->has_vnet_hdr once in packet_snd (da7c9561) · Commits · 戴 / test

Packet socket option po->has_vnet_hdr can be updated concurrently with other operations if no ring is attached. Do not test the option twice in packet_snd, as the value may change in between calls. A race on setsockopt disable may cause a packet > mtu to be sent without having GSO options set. Fixes: ("packet: Add GSO/csum offload support.") Signed-off-by:

Willem de Bruijn <willemb@google.com> Reviewed-by:

Eric Dumazet <edumazet@google.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

net/packet/af_packet.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -2840,6 +2840,7 @@ static int packet_snd(struct socket sock, struct msghdr msg, size_t len)
		struct virtio_net_hdr vnet_hdr = { 0 };
		int offset = 0;
		struct packet_sock *po = pkt_sk(sk);
		bool has_vnet_hdr = false;
		int hlen, tlen, linear;
		int extra_len = 0;

		@@ -2883,6 +2884,7 @@ static int packet_snd(struct socket sock, struct msghdr msg, size_t len)
		err = packet_snd_vnet_parse(msg, &len, &vnet_hdr);
		if (err)
		goto out_unlock;
		has_vnet_hdr = true;
		}

		if (unlikely(sock_flag(sk, SOCK_NOFCS))) {
		@@ -2941,7 +2943,7 @@ static int packet_snd(struct socket sock, struct msghdr msg, size_t len)
		skb->priority = sk->sk_priority;
		skb->mark = sockc.mark;

		if (po->has_vnet_hdr) {
		if (has_vnet_hdr) {
		err = virtio_net_hdr_to_skb(skb, &vnet_hdr, vio_le());
		if (err)
		goto out_free;

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